A light emitting diode (LED) is a semiconductor light emitting device converting a current into light.
The wavelength of light emitted from the LED depends on a semiconductor material used for manufacturing the LED because the wavelength of the emitted light depends on a band-gap of a semiconductor material representing an energy difference between electrons in a valence band and electrons in a conduction band.
Recently, as the brightness of the LED increases more and more, the LED is used as a light source for a display device, a lighting apparatus, and a light source for an automobile. The LED can be realized to emit white light with excellent efficiency by using a fluorescent material or combining LEDs of various colors.
To use the LED for this purpose, the operation voltage of a device should be lowered and a light emitting efficiency and brightness should be high.
In manufacturing such an LED, a silicon gel or an epoxy resin is coated on an LED chip of a package to increase efficiency and protect the LED chip. At this point, a method for coating a silicon gel or an epoxy resin, and a coating shape have a great influence on a light emitting efficiency.
Also, recently, a light emitting device package includes a lens to increase a light emitting efficiency. Such a lens not only increases a light emitting efficiency but also controls light distribution characteristic to a desired angle.
In a method of realizing various colors of an LED, a method of coating phosphor on an LED chip to realize various colors is generally used. At this point, a light emitting efficiency can change depending on a method and a position by which the phosphors are coated.